Hi, Enric: On Fri, 2020-02-21 at 09:56 +0100, Enric Balletbo i Serra wrote: > Hi CK, > > Thanks for your quick answer. > > On 21/2/20 5:39, CK Hu wrote: > > Hi, Enric: > > > > On Thu, 2020-02-20 at 18:21 +0100, Enric Balletbo i Serra wrote: > >> Dear all, > >> > >> Those patches are intended to solve an old standing issue on some > >> Mediatek devices (mt8173, mt2701 and mt2712) in a slightly different way > >> to the precedent series. > >> > >> Up to now both drivers, clock and drm are probed with the same device tree > >> compatible. But only the first driver get probed, which in effect breaks > >> graphics on those devices. > >> > >> The version eight of the series tries to solve the problem with a > >> different approach than the previous series but similar to how is solved > >> on other Mediatek devices. > >> > >> The MMSYS (Multimedia subsystem) in Mediatek SoCs has some registers to > >> control clock gates (which is used in the clk driver) and some registers > >> to set the routing and enable the differnet blocks of the display > >> and MDP (Media Data Path) subsystem. On this series the clk driver is > >> not a pure clock controller but a system controller that can provide > >> access to the shared registers between the different drivers that need > >> it (mediatek-drm and mediatek-mdp). And the biggest change is, that in > >> this version, clk driver is the entry point (parent) which will trigger > >> the probe of the corresponding mediatek-drm driver and pass its MMSYS > >> platform data for display configuration. > > > > When mmsys is a system controller, I prefer to place mmsys in > > drivers/soc/mediatek, and it share registers for clock, display, and mdp > > driver. This means the probe function is placed in > > drivers/soc/mediatek ,its display clock function, mdp clock function are > > placed in drivers/clk, display routing are placed in drivers/gpu/drm, > > and mdp routing are placed in dirvers/video. > > > > I understand what you mean but I am not sure this makes the code clearer and > useful. The driver in drivers/soc/mediatek will be a simple dummy implementation > of a "simple-mfd" device (a driver that simply matches with > "mediatek,mt8173-mmsys" and instantiates the "clk-mt8173-mm" and the > "mediatek-drm" driver (note that mediatek-mdp" is already instantiated via > device-tree). > It's clear that mmsys is neither a pure clock controller nor a pure routing controller for display and mdp. > It'd be nice had a proper device-tree with a "simple-mfd" for mmsys from the > beginning representing how really hardwware is, but I think that, change this > now, will break backward compatibility. Maybe this is a solution. Current device tree would work only on old kernel version with a bug, so this mean there is no any device tree works on kernel version without bug. Why do we compatible with such device tree? Regards, CK > > IMHO I think that considering the clk driver as entry point is fine, but this is > something that the clock maintainers should decide. > > Also note that this is not only a MT8173 problem I am seeing the same problem on > all other Mediatek SoCs. > > Thanks. > > > Regards, > > CK > > > >> > >> All this series was tested on the Acer R13 Chromebook only. > >> > >> For reference, here are the links to the old discussions: > >> > >> * v7: https://patchwork.kernel.org/project/linux-mediatek/list/?series=241217 > >> * v6: https://patchwork.kernel.org/project/linux-mediatek/list/?series=213219 > >> * v5: https://patchwork.kernel.org/project/linux-mediatek/list/?series=44063 > >> * v4: > >> * https://patchwork.kernel.org/patch/10530871/ > >> * https://patchwork.kernel.org/patch/10530883/ > >> * https://patchwork.kernel.org/patch/10530885/ > >> * https://patchwork.kernel.org/patch/10530911/ > >> * https://patchwork.kernel.org/patch/10530913/ > >> * v3: > >> * https://patchwork.kernel.org/patch/10367857/ > >> * https://patchwork.kernel.org/patch/10367861/ > >> * https://patchwork.kernel.org/patch/10367877/ > >> * https://patchwork.kernel.org/patch/10367875/ > >> * https://patchwork.kernel.org/patch/10367885/ > >> * https://patchwork.kernel.org/patch/10367883/ > >> * https://patchwork.kernel.org/patch/10367889/ > >> * https://patchwork.kernel.org/patch/10367907/ > >> * https://patchwork.kernel.org/patch/10367909/ > >> * https://patchwork.kernel.org/patch/10367905/ > >> * v2: No relevant discussion, see v3 > >> * v1: > >> * https://patchwork.kernel.org/patch/10016497/ > >> * https://patchwork.kernel.org/patch/10016499/ > >> * https://patchwork.kernel.org/patch/10016505/ > >> * https://patchwork.kernel.org/patch/10016507/ > >> > >> Best regards, > >> Enric > >> > >> Changes in v8: > >> - Be a builtin_platform_driver like other mediatek mmsys drivers. > >> - New patches introduced in this series. > >> > >> Changes in v7: > >> - Add R-by from CK > >> - Add R-by from CK > >> - Fix check of return value of of_clk_get > >> - Fix identation > >> - Free clk_data->clks as well > >> - Get rid of private data structure > >> > >> Enric Balletbo i Serra (2): > >> drm/mediatek: Move MMSYS configuration to include/linux/platform_data > >> clk/drm: mediatek: Fix mediatek-drm device probing > >> > >> Matthias Brugger (4): > >> drm/mediatek: Use regmap for register access > >> drm/mediatek: Omit warning on probe defers > >> media: mtk-mdp: Check return value of of_clk_get > >> clk: mediatek: mt8173: Switch MMSYS to platform driver > >> > >> drivers/clk/mediatek/Kconfig | 6 + > >> drivers/clk/mediatek/Makefile | 1 + > >> drivers/clk/mediatek/clk-mt2701-mm.c | 30 +++ > >> drivers/clk/mediatek/clk-mt2712-mm.c | 44 +++++ > >> drivers/clk/mediatek/clk-mt8173-mm.c | 172 ++++++++++++++++++ > >> drivers/clk/mediatek/clk-mt8173.c | 104 ----------- > >> drivers/gpu/drm/mediatek/mtk_disp_color.c | 5 +- > >> drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 5 +- > >> drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 5 +- > >> drivers/gpu/drm/mediatek/mtk_dpi.c | 12 +- > >> drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 4 +- > >> drivers/gpu/drm/mediatek/mtk_drm_ddp.c | 53 +++--- > >> drivers/gpu/drm/mediatek/mtk_drm_ddp.h | 4 +- > >> drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h | 56 +----- > >> drivers/gpu/drm/mediatek/mtk_drm_drv.c | 113 +----------- > >> drivers/gpu/drm/mediatek/mtk_drm_drv.h | 13 +- > >> drivers/gpu/drm/mediatek/mtk_dsi.c | 8 +- > >> drivers/gpu/drm/mediatek/mtk_hdmi.c | 4 +- > >> drivers/media/platform/mtk-mdp/mtk_mdp_comp.c | 6 + > >> include/linux/platform_data/mtk_mmsys.h | 73 ++++++++ > >> 20 files changed, 401 insertions(+), 317 deletions(-) > >> create mode 100644 drivers/clk/mediatek/clk-mt8173-mm.c > >> create mode 100644 include/linux/platform_data/mtk_mmsys.h > >> > > > > _______________________________________________ > Linux-mediatek mailing list > Linux-mediatek@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-mediatek
